1. Field of the Invention
The present invention relates to a controller apparatus for a faucet, and in particular relates to a controller apparatus including a function of electric power generation.
2. Discussion of the Background
The purpose of driving a controller apparatus for a faucet or tap by a function of electric power generation is to eliminate all engineering works and/or maintenances relating to a power supply of that apparatus. However, if the apparatus fails to operate or needs periodical exchange of components thereof, depending upon the condition of use, there is no purpose for providing the function of generating electricity.
The details of a related apparatus according to the conventional art can be seen in Japanese Utility Model Publication No. Hei 6-37096 (1994) and are described as follows:
In an apparatus, wherein the power generator is driven by an impeller which is provided within a flow passage of a faucet, so that a storage battery is charged with this power generator, and electricity is supplied to a faucet controller (a controller circuit) by means of the storage battery, there is provided a dry cell for unforeseen shortage in the charge of the storage battery, thereby to supply electricity to the faucet controller even from that dry cell. The dry cell is provided for the purpose of protecting the controller from stoppage of the operation thereof when the electric power generation comes down in shortage in an amount thereof.
According to such a conventional invention, the storage battery is provided as a main power supply for the controller circuit, while current providing power supply to the controller circuit is provided from the dry cell when the voltage of the storage battery is not sufficient. However, this arrangement has the following problems:
First, though the storage battery is applied in the main power supply, however, the number of usable years thereof, i.e., the service-life thereof, is short compared to other electronic components, for example, a resistor, a capacitor, etc. The storage battery is suitable for application in devices such as portable apparatuses, power tools, toys, etc., to which the dry cell is not well suited as a power supply and uneconomic since these devices have high power consumption. On the contrary, the storage battery is inherently not-suited for an application like a faucet apparatus, which is designed to be used for a long time with very little power consumption.
There are known various charging methods being appropriate for storage batteries, depending upon the kind thereof, such as charging with constant voltage, charging with low current, monitoring of change of temperature, etc. and also, there are restrictions of conditions for discharging thereof, such as current value, etc. If not operated according to such methods and/or conditions, the storage battery is overcharged or over-discharged, which tends to significantly deteriorate the performance thereof.
In the method of charging by means of the power generator driven when emitting water, since the time during which the power generation is conducted is short, a large amount of electric power is generated in an instant, and further the timing thereof is not predictable. Not seen in the conventional art, but in a case where a solar battery is applied as the power generator, a large amount of current flows continuously for several hours during clear weather, and this may continue for days. In the same manner, in a case where the electric power is generated by means of a thermal power generation element using the difference in temperature between hot water and cold water, it is difficult to control the power generation.
In any one of the cases of using such methods as the hydroelectric power generation, the solar battery and the thermal power generation, distinct from a case where a user intentionally charges the storage battery using a charger and so on, the charging conditions change variously depending upon the situations. It is difficult to satisfy a rule of charging which is recommended to avoid deterioration of the storage battery, and in such instances the shortening of the service-life of the storage battery can be unavoidable.
As is mentioned in the above, since there is applied the storage battery which in general is understood to not have a notably long service-life, and further since according to the possible conditions of use for this application it may be charged only through an inappropriate method, it is anticipated that the storage battery must be replaced within several years. Therefore, using the storage battery, since exchange of the storage battery will be necessary before the service-life of the faucet apparatus, it is impossible to achieve the purpose of the apparatus, i.e., its being maintenance-free. Therefore, it must be said that such use of the storage battery is not appropriate.
Also, according to the conventional art, the storage battery and the dry cell are connected in parallel with respect to the controller circuit, and electricity is conducted or supplied from either or both of the battery and the cell. The method, according to such a conventional art, is to switch the active source from among the battery and the cell depending upon the voltage difference between the battery and the cell, using diodes therein. However, this has such a problem, which will be mentioned below.
Using the storage battery and the dry cell in an exchangeable manner requires that the storage battery and the dry cell must be relatively equal in the performance or capacities thereof. Main consumption is the driving of an electromagnetic valve within the controller circuit for the faucet, and it is conventional to adopt one or several latching solenoids for keeping the electromagnetic valve in an OPEN- or CLOSE-condition in the faucet apparatus using the battery and the cell therein, however this necessitates a large amount of current being supplied in an instant. Therefore, in the conventional art, both the storage battery and the dry cell must be ones each having a capacity for supplying a large amount of current therefrom.
A long-term durable dry cell, having a service-life of 10 years, for example, has been developed for use in a gas meter, in which it is employed for a long time period using a very small amount of current. Because the internal resistance of the battery is large, it is therefore not suitable for the purpose of supplying a large amount of current therefrom. If such a large amount of current flows through, the dry cell is deteriorated and the service-life thereof comes to be about several years in the same manner as of the storage battery, thereby being contrary to the purpose, i.e., maintenance-free operation, of the electric power supply mentioned in the above.
Also, it is very difficult to clearly switch between the storage battery and the dry cell, in practice. Both the storage battery and the dry cell exhibit a lowering of the output voltage when the electric power remaining therein comes to be small, but the capacities thereof are variable depending on the kinds of the battery and the call. The capacities are changed depending on not only the remaining power, but also an environmental factor, such as the temperature, and the relative influence of such factors is also variable depending on the kind of the battery and the cell.
A nickel-cadmium battery in the conventional art is a type of the battery which has discharge characteristic being relatively flat, and it maintains the output of around 1.2 V during a discharge period thereof, but thereafter supplied voltage drops sharply. When voltage of the storage battery decreases sharply, the battery is in the condition where it is almost over-discharged, and also, the capacity of supplying current decreases remarkably, so that it is impossible to drive the controller circuit.
Therefore, it is necessary to switch from the storage battery to the dry cell before the former reaches an over-discharged state characterized by a sharp drop in available voltage, however since the duration of the condition wherein the nickel-cadmium battery maintains the constant battery voltage is long, both the dry cell and the storage battery are exhausted at the same time in most cases. Because the dry cell also changes the voltage gradually depending upon the remaining power in the cell, it is impossible to switch based on a boundary threshold set at a certain voltage, therefore it is impossible to escape from the fact that the dry cell is exhausted at the same time when the storage battery is exhausted.
Also, once the voltage of the storage battery decreases, a relatively large amount of charge is necessary to restore the output voltage. Therefore, the consumption of the dry cell is continued even if the power generation is conducted to the storage battery. Moreover, since the dry cell is also used for charging of the storage battery, it must share a loss of self-discharge of the storage battery and the heat generation when charging the storage battery. Therefore, the consumption of the dry cell comes to be greater, with most of the capacity of the cell being consumed once starting the operation thereof, and the service life of the dry cell therefore comes to be short.
With such a method according to the conventional art, because the electricity can be supplied to the controller circuit for the faucet from both the storage battery and the dry cell, the dry cell is inadvertently consumed, though it should be used primarily in a case where the remaining power of the storage battery is insufficient. Therefore, there is a possibility that the power remaining in the dry cell is insufficient when it is actually needed. Also, since it is impossible to determine whether either of the storage battery and the dry cell is actually used, an estimate cannot be made for a pace of consumption of the dry cell, and the dry cell must be replaced with new one, earlier with a margin. This is also, as is mentioned previously, contrary to the purpose of achieving the maintenance-free electric power supply by means of the electric power generation.
As is mentioned in the above, with the method of switching between the storage battery and the dry cell when conducting the electricity to the controller circuit, the storage battery and the dry cell reach the respective service-life thereof more quickly than under nominal applications thereof, depending on the characteristics of the battery and the cell which are actually used, and therefore it is impossible to achieve the apparatus's purpose of being maintenance-free.
Also, in the case where the hydroelectric generator including a water wheel and a power generator therein is provided as a power generation means, another problem arises additional to the problem limiting the maintenance-free requirement.
As a well-known characteristic of a power generator, when output current is drawn from the power generator, torque is generated due to electromagnetic force of this current in the direction preventing (opposite to) the rotation of the power generator. This means that the rotation of the water wheel, which is attached to the power generator, is prevented, and pressure loss in a portion of the hydroelectric generator is increased, thereby decreasing the flow rate of the faucet apparatus.
The generator is provided for the purpose of charging the storage means as the electric power supply for the faucet apparatus, and the flow rate of the faucet apparatus is set appropriately such that it outputs the charging current therefrom.
However, when the storage means is in a condition of being fully-charged and does not need any charge or is prohibited from charging, the current from the generator, being generated as the charge current until then, has no destination to flow to. In this instance, the output current of the generator comes to be zero (0), and the pressure loss in the portion of the hydroelectric generator is decreased while proportionally increasing the flow rate in the faucet apparatus.
In this manner, in the case of the hydroelectric power generation, the load current of the generator changes depending on whether it charges the storage battery or not, and there is a problem that the flow rate in the faucet apparatus changes without regard to the intention of a user.
For example, in Japanese Utility Model Laid-open No. Hei 2-65046 (1990), there is disclosed “connecting the power generator to the storage battery only when the storage battery is not yet fully charged”. In this case, since the power generator loses the load when the storage battery is fully charged, the flow rate in the faucet rises abruptly when the charging of the storage battery is completed, as is mentioned previously.